Perfluoroalkylethyl iodides, CkF(2k+1)CH2CH2I, termed “Telomer B iodides”, are prepared by insertion of an ethylene molecule into the perfluoroalkyl iodides of the structure CkF(2k+1)I, “termed Telomer A iodides”. Perfluoroalkylethyl iodides are starting materials for the preparation of fluorinated surfactants and treatment chemicals to provide surfaces with hydrophobic and oleophobic properties. Compounds made from such iodides include, for example, perfluoroalkylethyl(meth)acrylates and various other compounds containing the perfluoroalkylethyl group, and find commercial use in the modification of surface properties. See, for example U.S. Pat. No. 3,721,706.
For surfactants and surface treatment agents with fluorochemical chains longer perfluoroalkyl chains contain a higher percentage of fluorine at a given concentration and provide better performance. However, fluorinated materials are more expensive. Reduction of the fluorine content with delivery of the same or higher performance is therefore desirable. Reducing the fluorine content would reduce the cost, but it is necessary to maintain product performance.
It is desirable to improve surfactant or surface treating agent performance and to increase the fluorine efficiency, i.e., boost the efficiency or performance of the surfactants or treating agents so a lower proportion of the expensive fluorine component is required to achieve the same level of performance, or to have better performance using the same level of fluorine. It is also desirable to have an economical pathway for preparation of such fluorine efficient surfactants and surface treating agents from perfluoroalkyliodides.
Two methods for the preparation of perfluoroalkylethyl(meth)acrylates from perfluoroalkyliodides are:    (1) reaction of the perfluoroalkylethyl iodide with a (meth)acrylic acid salt such as potassium (meth)acrylate, as described by Fasick et al. in U.S. Pat. No. 3,239,447; and    (2) reaction of the perfluoroalkylethyl iodide with oleum and further hydrolysis of the sulfates with water in sulfuric acid to yield perfluoroalkylethanol, as described by Day in U.S. Pat. No. 3,283,012, followed by esterification with (meth)acrylic acid or transesterification with an alkyl (meth)acrylate.The first process is accomplished in a single step but yields are lowered by the formation of byproduct perfluoroalkylethylene. The second process involves two reaction steps, the use of oleum and sulfur trioxide, but is free of byproduct perfluoroalkylethylene.
There is a need for surfactants and surface treating agents providing equivalent or improved performance while reducing the proportion of fluorine required due to its expense, and for economical pathways to such products. The present invention provides such surfactants having higher fluorine efficiency and an improved method of making certain surfactants.